[The structures of yemuoside YM10 and YM12 from Stauntonia chinensis]

Two new nortriterpenoid saponins, named yemuoside YM10 (I) and YM12 (II), were isolated from Stauntonia chinensis Decne. A new prosaponin (VI) was isolated from the cleavage of ester-glycoside linkage. Their chemical structures were elucidated by means of chemical and spectrometric analysis. Yemuoside YM10 (I): C58H92O25, a white powder, mp 215-219 degrees C (dec), [alpha]D20-4.41 degrees (c 0.272, CH3OH). Its structure was found to be 28-O-alpha-L-rhamnopyranosyl- (1----4) -beta-D-glucopyranosyl- (1----6) -beta-D-glucopyranosyl ester of 3-O-alpha-L-rhamnopyranosyl-(1----2)-alpha-L-arabinopyranosyl-30-+ ++norolean-12, 20 (29) -dien-28-oic acid. Yemuoside YM12 (II): C52H82O21, a white powder, mp 200-204 degrees C (dec.), [alpha]D20 + 10.12 degrees (c 0.346, CH3OH). Its structure was found to be 28-O-beta-D-glucopyranosyl- (1----6) -beta-D-glucopyranosyl ester of 3-O-alpha-L-rhamnopyranosyl- (1----2) -alpha-L-arabinopyranosyl-30-norolean-12, 20 (29)-dien-28-oic acid. Prosaponin (VI): C40H62O11, a white powder, mp 243-246 degrees C (dec.), [alpha]D22 + 12.13 degrees (c 0.128, CH3OH). Its structure was found to be 3-O-alpha-L-rhamnopyranosyl- (1----2)-alpha-L-arabinopyranosyl-30-norolean-12, 20 (29)-dien-28-oic acid.